Rep. Eliot L. Engel, a New York Democrat, is ranking member of the US House Committee on Foreign Affairs. Anders Fogh Rasmussen is former NATO secretary general and former Prime Minister of Denmark. The views expressed in this commentary are their own.

(CNN) This week, President Donald Trump will travel to the NATO summit in Brussels. America's allies will pay close attention to his every word and seek strong reassurances that the United States will continue to play a leading role in the critical alliance. We sincerely hope he provides those reassurances.

NATO is not, as Trump has stated , taking advantage of the United States. The alliance was forged out of the ashes of two world wars under American leadership. Together, the allies honored those hundreds of thousands of service members who lost their lives by building a system to prevent such conflicts from igniting again.

Eliot L. Engels

Anders Fogh Rasmussen

The relative peace and stability that NATO and other postwar institutions provided the United States and Europe in the late 20th century cannot be underestimated. With American leadership, allied democracies created the conditions for unparalleled prosperity for ordinary Americans and Europeans alike -- and defeated the communist threat.

Today, that world is facing renewed danger, and our common challenges are no less significant. They include the growing Russian threat, transnational terrorism, cyberwarfare, piracy on the high seas and the proliferation of weapons of mass destruction, among others. Just as the United States underpinned NATO's resolve to provide collective security against the Soviet Union, an American retreat today will allow autocrats and dictators to advance.

NATO is engaged around the world, supporting a range of interests critical to the United States and its partners. NATO allies continue to uphold the concept of collective defense -- an attack on one is an attack on all. This commitment was put into practice for the first and only time in NATO history after September 11, 2001, when NATO forces stood shoulder to shoulder in support of the United States.

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