Despite protests both in the United States and abroad, the Trump administration’s decision to withdraw from the 1992 Treaty on Open Skies (OST) is fully justified for a whole raft of rock-solid reasons.

Going back a decade now, Russia has been blatantly violating the 34-nation confidence- and security-building treaty, which allows unarmed aerial observation flights over member states’ territory in the interest of military transparency.

Using onboard cameras, OST missions—if conducted as the treaty envisions—can potentially provide early warning of military aggression, observe ongoing exercises and even potentially help verify arms-control and other agreements.

But that isn’t happening due to Moscow’s failure to comply.

The list of Russian violations is unfortunately long. In 2010 Moscow started preventing OST observation flights from approaching to within 10 kilometers of Russia’s border with the Georgian regions of South Ossetia and Abkhaz.

While South Ossetia and Abkhazia are within the borders of Georgia, Moscow considers these Russian-occupied areas to be “independent” states and, therefore, not party to the OST. As such, OST missions can’t observe them under the treaty. Or so goes the Russian argument.

Then there is the Kremlin’s restriction on OST flights to 500 kilometers in length over the Russian highly-militarized exclave of Kaliningrad, located between NATO members Lithuania and Poland on the Baltic Sea.

That transgression goes back to 2014.

In addition, last September, Moscow denied a request for a U.S. OST plane to fly over the Russian Tsentr-2019 strategic-level exercises; the military drills included China and others and involved upwards of 120,000 troops.

Also of concern, the U.S. Director of National Intelligence noted recently that, “For years, Russia has used the Open Skies Treaty to collect intelligence on civilian infrastructure and other sensitive sites in America, posing an unacceptable risk to our national security.”

Exiting the OST will put a stop to such activity.

The latest OST provocation is Russia’s propaganda move of designating an airfield in illegally-annexed Crimea for Open Skies aircraft use. It asserts through OST that the Peninsula is a part of Russia, rather than Ukraine.

Cost is also an issue. The U.S. Air Force’s two Open Skies OC-135 aircraft are old and need to be replaced. In addition to its annual operating costs, replacing the OC-135 with newer airframes could cost some $200 million.

Plus, it’s also fair to assert that the photographic imagery taken on OST missions, while releasable to all OST member states, has been succeeded by high-tech satellite systems that provide potentially better information more quickly.

To its credit, despite clear-cut Russian violations, the Trump administration undertook a months-long, interagency review of the costs and benefits of continuing in the OST.

The administration also consulted closely with OST allies and partners before making its final decision. It of course has made its concerns known to the Russian side, which chose to remain in breach of the treaty protocols despite protests.

In the end, the Trump administration judged that Russia is willfully breaking and abusing the OST. The openness, transparency, cooperation and trust that uphold military confidence- and security-building measures cannot happen unless both sides abide by them.

In addition, as a general principle, there must be consequences for non-compliance with a treaty. Continuing to ignore OST violations could encourage additional Russian bad behavior in arms control—and potentially elsewhere.

Moreover, Moscow’s violations of the OST adds to deep-seated concerns about Russian belligerence in Europe, including violations of, and participation in, other security treaties.

It’s important not to forget its egregious material breach of the Intermediate-Range Nuclear Forces (INF) Treaty, its suspension of participation in the Conventional Armed Forces in Europe (CFE) Treaty, and its defiance of the Chemical Weapons Convention (CWC).

Thoughtfully, President Trump is open to remaining in the treaty if Russia comes back into compliance, saying: “Russia didn’t adhere to the treaty. So until they adhere, we will pull out ... But there’s a very good chance we’ll make a new agreement or do something to put that agreement back together.”

The United States is well within its rights to begin the six-month withdrawal process from the OST—and the White House’s decision to do so rests squarely on the Kremlin’s willful violations of the nearly three-decades-old treaty.