Alyssa Ayres is senior fellow for India, Pakistan and South Asia at the Council on Foreign Relations and the author of "Our Time Has Come: How India is Making Its Place in the World." The views expressed in this commentary belong solely to the author. View more opinion at CNN.

(CNN) A suicide bomber drove a vehicle filled with explosives into an Indian paramilitary convoy in Pulwama, in the Indian state of Jammu and Kashmir, on February 14. The death toll is at least 40 , making it the largest attack in Kashmir in three decades. A Pakistan-based terrorist group, Jaish-e-Muhammad, claimed responsibility through a video released shortly after.

That this terrorist group, nominally banned, remains at large in Pakistan illustrates the limitations on US foreign policy tools. It also means the US should put even more pressure on Pakistan, after President Trump began his time in office taking a harder line.

A year ago, the Trump administration suspended security assistance to Pakistan as punishment for the country's hosting of terrorist groups that attack Afghanistan. But Pakistan still allows internationally designated terrorists to operate openly and plot attacks on its neighbors, according to the US , India and independent experts. This spells bad news not only for India-Pakistan relations, already at a low and about to sink further, but also for security in South Asia more generally—especially with a negotiation process underway on the US presence in Afghanistan.

The resurgence of the nearly two-decade-old Jaish-e-Muhammad (JeM) is frightening. The United States and the UN Security Council designated it as a terrorist organization in 2001. In December 2001 JeM attacked the Indian parliament and raised fears of a full-scale war between India and Pakistan. Its Pakistani leader, Maulana Masood Azhar, founded the group in 2000 after his release from Indian prison in a deal that included around 150 hostages in an Indian Airlines plane hijacked to Taliban-controlled Kandahar the previous year. (One of Mr. Azhar's fellow releasees, Ahmed Omar Saeed Shaikh , lured Wall Street Journal reporter Daniel Pearl to his murder in 2002.)

Pakistani authorities over the years have "cracked down" on Jaish-e-Muhammad by holding Azhar under house arrest at various times, only to release him later—revealing Pakistan's dubious commitment to seriously addressing extremist groups.

The group has grown more active in recent years. India holds it responsible for attacking an air force base in Pathankot, India, in January 2016, and Pakistan arrested Azhar over the incident, though he was later released. Then, in September 2016, the group attacked an Indian Army base in Uri, in a remote part of Jammu and Kashmir, killing 19 soldiers.

The Uri attack culminated a series of terrorist incidents and raised tensions significantly. It led Indian forces to mount a "surgical strike" across the Line of Control, the cease-fire line between India and Pakistan in Kashmir, to preempt yet another cross-border attack from Pakistan. India has suspended dialogue with Pakistan without clear action against these terrorist groups. What's more, with national elections looming in India, Prime Minister Narendra Modi faces enormous pressure to at minimum respond as he did with Uri. He has already tweeted that a "befitting reply will be given" to the attackers.

It has been hard for the United States to identify the right combination of policies that would compel Pakistan to act further against terrorists. The Obama administration, by the end of its time in office, began restricting security assistance and designated more terrorist entities and individuals in an effort to get Pakistan to step up against the variety of terrorists operating on its soil. In 2016, after the Uri attack, US National Security Advisor Susan Rice condemned the violence and singled out Pakistan's responsibility to "take effective action" against JeM and other terrorist groups there.

The Trump administration has taken a harder line on Pakistan—but the strategy has yet to pan out, and the administration would do well to go further.

Within a year of taking office the Trump administration cut off security aid to Pakistan. On January 1, 2018, the president tweeted that Pakistan had given nothing but "lies and deceit" and was harboring terrorists despite receiving billions in US assistance. Days later, the administration suspended all security assistance to Pakistan, pending the country's "decisive action" against terrorist groups. Last June, an international group formed to coordinate on counter-terrorist financing and money laundering, the Financial Action Task Force (FATF), placed Pakistan on a "gray list" and ordered it to "address its strategic counter-terrorist financing-related deficiencies" if it wanted to remain part of international financial networks.

Yet a year on, it's hard to argue that cutting off the security funding has been enough. Hafiz Saeed, a terrorist on numerous US and UN designation lists, continues to hold large public rallies about Kashmir in Pakistan, and even tried to register a political party last year. Terrorist-linked and other militant candidates ran for office in the country's national elections of July 2018. An investigative report from India last summer found that Jaish had vastly expanded its headquarters facility. To put it mildly, none of this looks like decisive steps to rein in terror, as Pakistan claims.

The Trump administration has further policy tools it could employ. Options include revoking Pakistan's Major Non-NATO Ally status, banning specific individuals from travel to the US, refusing to support an International Monetary Fund bailout, blacklisting (not just graylisting) on the FATF or attempting once again to secure the individual designation of Jaish-e-Muhammad head Masood Azhar on UN Security Council sanctions lists. (China has blocked Security Council efforts in the past.) The Trump administration will also undoubtedly weigh the effect of applying greater pressure on Pakistan at a time it is trying to negotiate—with Pakistan's help—an end to the US presence in Afghanistan.

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But increasing pressure on Pakistan is the right thing to do now. Pakistan has refused to take responsible action against terrorists within its borders, failing its obligations under UN Security Council sanctions. Its refusal to do so is singularly damaging to regional security. Terrorist attacks have disrupted every attempt at peace between India and Pakistan, and Pakistan-based terrorists remain a threat to peace in Afghanistan. (Remember, it's the Taliban who negotiated the release of JeM founder Azhar back in 1999.)

In this context, an exit from Afghanistan that doesn't risk decline into instability has to include sustained, verifiable action from Pakistan against terrorism. This is precisely why further pressure from Washington and other capitals on Pakistan is so important: The provocation originates there. To maintain peace in this crucial region, it should be stopped there.