Jeremiah 18:7
At what instant I shall speak concerning a nation, and concerning a kingdom, to pluck up, and to pull down, and to destroy it; At what instant I shall speak concerning a nation, and concerning a kingdom, to pluck up, and to pull down, and to destroy it;
God holds authority over nations and kingdoms as a potter holds authority over clay, shaping and reshaping according to His rightful sovereignty. In exercise of that authority He may at any moment speak concerning a nation and concerning a kingdom to pluck it up and pull it down and destroy it, announcing its uprooting, overthrow, and destruction. He also has power to bring a nation or kingdom down.
That announced judgment is conditional, as the verses that follow explain: if the nation against which He has spoken turns from its evil, He will relent from the disaster He intended and the nation may be spared from the calamity. His dealings with nations are therefore not fixed regardless of their choices but depend on their course of action. A nation that forsakes sin and turns to God is not condemned for its ancestors' sins.
As the following verses show, He can also build up a nation or kingdom. Both bringing down and building up are consistent with His unchanging character, which is always on the side of righteousness and truth.
In its setting the message called Judah to repent and mend its ways, yet the people rejected the warning and chose their own evil course. They refused the call to repent and plotted against Jeremiah, showing that God's people cannot resist His work or silence the message He sends. The verse thus carries God's warning plea for His people to stop doing evil and learn to do what is right.