Nirmala Sitharaman takes charge at a critical time for India.
Sitharaman's immediate security challenges are evident.
These domestic fault-lines in Pakistan could cause real tremors across the border in India.
Sharif was a strong advocate of dialogue with India; now, with the civilian establishment weakened and the Pakistani army potentially calling the shots on foreign policy, India must prepare for any number of possibilities, including a greater surge in terrorist violence.
In 2016, a total of 64 Indian soldiers were killed in terrorist assaults in Jammu and Kashmir
, the highest figure in six years; the political uncertainty in Pakistan pretty much closes the prospect of any effective dialogue between the two countries at the moment. So, Sitharaman will have to be alert to the possibility of those numbers increasing.
The China threat
With China, India is fighting a two pronged-battle. Its road and infrastructure projects are seen in India to be a sophisticated economic cloak thrown over marauding neo-imperialism
. Sitharaman will have to contend with the dare of China's One Belt, One Road Initiative (OBOR) -- an audacious network of land and sea routes that seeks to connect Asia, Europe, Africa and the Middle East in a modern, magnified version of the Silk Route.
What irks India is that part of the OBOR known as the China Pakistan Economic Corridor runs through Gilgit-Baltistan, territory that India sees as sovereign and illegally occupied
, all the way to the Gwadar deep-sea port in Pakistan.
India skipped the China-hosted OBOR summit and is the only South Asian country to not sign its framework agreement.
Sitharaman's management of India's relationship with China will be much trickier than managing Pakistan.
India and China are home to 36% of the world's population and a conflict of any kind could be catastrophic.
But China is also India's largest business partner with a bilateral trade worth more than 70 billion dollars
In August, the Indian government scored a diplomatic win with China in a long-running border dispute, that at one point, saw soldiers from both countries locked eyeball-to-eyeball in the mountain kingdom of Bhutan.
The situation had erupted after the Chinese expanded a road in territory Bhutan, a close ally of India, claims as its own.
Modi indicated he would skip a multilateral forum of the BRICS countries (Brazil, Russia, India, China and South Africa) in Xiamen, if China's bulldozers did not stand down. On the eve of the summit, the status quo was restored, and troops from both sides retreated.
At the BRICS summit, a first of its kind resolution was passed
that bracketed Pakistan-headquartered terror groups like the Lashkar-E-Taiba and the Jaish-E-Mohammad with global terror groups, such as the Islamic State and al-Qaeda.
But China seemingly reneged on this commitment in less than a week, praising Pakistan for having a "clear conscience" on fighting terrorism.
India's new defense minister will have to contend with the reality of Pakistan being "a client state of China" -- as one Indian official wryly called it -- a virtual Chinese colony in a post-colonial Asia.
While she hits the ground running with these external challenges, Sitharaman, known for her no-nonsense persona, may have to fight a battle of a slightly different kind on home turf -- the harsh scrutiny reality of sexism.
At 58, she is India's first full-time woman defense minister and heads a military that is 1.4 million strong and still mostly made up of men.
She earned her spurs as India's commerce minister when she led some prickly negotiations at the World Trade Organization (WTO).
Yet, no one -- in the media or her Bharatiya Janata Party -- could have forecast that the former spokeswoman of her party, who studied in a left-leaning university but always described herself as a 'free-thinker', would grab the coveted and powerful defense post.
Her appointment is as much about smashing a rock through the glass ceiling as it is about Prime Minister Narendra Modi's panache for audacity and surprise.
"Modi has a knack for thinking out of the box and confounding his critics," argues Manoj Ladwa, a party strategist who oversees communication and strategy for the BJP.
"Appointing Sitharaman, who was until not so long ago a political novice and an outsider, sends all the right signals. It also speaks volumes of her capability and potential, as winning Modi's trust is never easy," Ladwa told me.
In a historic first, India's cabinet committee on security -- the country's most powerful decision making group -- will now have two women: foreign affairs minister Sushma Swaraj and Sitharaman.
The only other woman to have ever led the defense ministry is Indira Gandhi, the former Prime Minister, who held the defense portfolio for a period of time.
Gandhi was often described as "the only man in her cabinet."
Back in the 70s that was the only way Indians knew how to reference a woman's tough, take-no-prisoners attitude -- by benchmarking it against male attributes.
35 years later, much has changed. But even in 2017, there are misogynistic murmurs about whether a post as critical as defense can afford to become an experimental symbol of gender equality.
A handful of critics have ventured to ask what specialization Sitharaman has for the job.
Ironically none of these questions were raised for her male predecessors, either in this government or the previous one -- thereby exposing the sexism inherent in the skepticism.
We are a paradoxical country. There are deep gender inequities that plague India -- a woman is raped every 22 minutes
, more than 7 million girls have been forced into marriage before the age of 10
-- and yet, we continue to leap over some of the barriers that hold back women in other parts of the world.
Abortion and a woman's right to choice is a non-issue.
We never had to fight for the vote. And, unlike the United States, we elected a female leader long ago.
Yet, the alpha-male world of the armed forces has in many ways remained the final frontier. It has been pried open slowly over the years. Last year India's Air force gave the thumbs up to female fighter pilots and the Navy is being nudged to allow women onto warships.
But the Army's combat arms, including its infantry, artillery and armored corps remain closed to women.
So, the symbolism of a woman in the defense ministry is potent and the expectations on Nirmala Sitharaman are enormous.
In August Sitharaman was in China talking trade. Now she will have to show them -- and the world -- and to the millions of Indian women celebrating her elevation that she means business.