Editor's note: Sen. Robert Menendez, D-New Jersey, is chairman of the Senate Foreign Relations Committee.
(CNN) -- During this period of stunning upheaval and chaos, where Russian actions in Ukraine are reminiscent of a bygone era of Soviet rule, we have arrived at a crossroads for the international order.
The question before us, from Washington to Warsaw, is not which direction will we turn, but rather how decisively we will move to support Ukraine in the face of Russia's illegitimate annexation of Crimea.
The aggression against Ukraine by a Russian president who romanticizes about Soviet greatness and views the last two decades as a historical misstep is the most recent example in a series of events involving disruptive Russian behavior throughout the world.
In Syria, President Vladimir Putin is actively propping up President Bashar al-Assad and perpetuating the world's worst humanitarian disaster.
In Iran, the ink of the Joint Plan of Action signed in Geneva, Switzerland, last November was barely dry when reports surfaced that Tehran and Moscow were negotiating an oil-for-goods swap worth $1.5 billion a month and plans were made public for joint Russia/Iran cooperation in building a new nuclear plant.
Today, our concern is for Ukraine. Tomorrow, it could be for Georgia again, or perhaps Moldova, two nations waiting to formalize closer ties to Europe through an association agreement with the European Union -- the exact same process Ukraine was pursuing to the displeasure of the Russian government.
Putin has miscalculated. He has ignited a dangerous Soviet-style game of Russian roulette with the international community, and we cannot blink. He must understand that we will never accept this violation of international law in Ukraine.
The unity of purpose displayed at the U.N. Security Council, by the EU and by the G7 nations in support of Ukrainian autonomy and in opposition to Russian authoritarianism demonstrates the world's outrage.
That collective attitude was punctuated by the EU agreeing on a framework for its first sanctions against Russia since the Cold War.
The Senate Foreign Relations Committee, where I serve as chairman, is playing an integral role in the U.S. response to this crisis.
The Senate overwhelmingly passed legislation on Thursday I sponsored with Ranking Member Bob Corker (R-TN) that provides an aid package of $1 billion in loan guarantees for Ukraine. It authorizes $50 million for democracy, governance and civil society assistance and $100 million for enhanced security cooperation for Ukraine and other states in Central and Eastern Europe.
It directs the Obama administration to assist the Ukrainian government in identifying, securing and recovering assets linked to acts of corruption by former Prime Minister Viktor Yanukovych, members of his family or other former or current Ukrainian government officials.
It requires additional sanctions, complementing the President's executive order, against Ukrainians and Russians alike responsible for violence and serious human rights abuses against anti-government protesters and those responsible for undermining the peace, security, stability, sovereignty or territorial integrity of Ukraine.
Finally, it authorizes sanctions on Russians complicit in or responsible for significant corruption in Ukraine.
Our international message of unity must be supported by demonstrating that the annexation of Crimea will not stand.
We are at a dangerous moment in history, with global consequences, and the world is watching.
If we do not act, what will China say when it's looking at its territorial desires in the South China Sea?
What will Iran say when we are negotiating about nuclear weapons?
What about North Korea, whose march to nuclear weapons on a greater scale is still in play?
Ukrainian sovereignty cannot be violated for simply looking westward and embracing ideals rooted in freedom. Those principles are the guideposts of our trans-Atlantic strategic response to international events, and we must respond together.
The challenge that faces us on both sides of the Atlantic is clear: Can a united trans-Atlantic vision and our collective commitment to bold actions in this century match the vision and commitment of those who created the international institutions which brought peace and prosperity to millions in the last century?
If the U.S. and our European allies live, lead, and govern, guided by shared values and united by our common concerns, we can play the stabilizing force for the world through these challenging times.
Congress will not be reticent in using all tools available in demonstrating our resolve that Russia's aggressive and brutal behavior is unacceptable.
The opinions expressed in this commentary are solely those of Sen. Robert Menendez.