Sen. Dianne Feinstein, D-Calif., called Wednesday for North Atlantic Treaty Organization allies to step up the fight against the Islamic State by invoking the self-defense clause.

In an op-ed in The Wall Street Journal, Feinstein argued that it was time to increase the number of NATO members in the fight from seven to 27.

"As Islamic State shifts its strategy, the U.S. and its allies should as well," Feinstein wrote. "The time has come for the North Atlantic Treaty Organization to invoke its self-defense clause so the full weight of the alliance is brought to bear against Islamic State, also known as ISIS."

Feinstein wrote that while the ISIS fighting force has fallen overall, they still remain a "significant threat" to the West, given their targeting of Europe and "lone wolf" attacks from Islamic State sympathizers. She also added that despite the reluctance to engage in a long war, Americans need to rethink the situation and "recognize" that an increased U.S. presence against the caliphate could help eliminate it.

"Yet the effort to maintain this momentum in the fight against Islamic State suffers from an inherent conflict. Americans don't want another prolonged war with thousands of service members deployed in combat operations, but the U.S.'s current strategy of airstrikes and limited assistance to on-the-ground partners isn't enough to defeat the terrorists," Feinstein wrote. "It is now time to recognize that an increased U.S. presence, acting with NATO countries and other partners, could enhance the effort to eliminate Islamic State."

The California Democrat added that the decision could help stabilize the Middle East, even though it would by no means rid the region of terror.

"Terrorism was around before al Qaeda and Islamic State and it will be around long after both groups have been defeated," Feinstein said. "But by doubling down in the fight against these terrorist groups now, the U.S., our NATO partners, and other allies will help stabilize the Middle East while making Americans and the rest of the world safer at home."

NATO has become a hot topic in the presidential election after Donald Trump floated the possibility of the U.S. not coming to an allied nations aid if they haven't paid their bills or reimbursed other nations for protection.